JP7400197B2 - Paper feeding device - Google Patents

Description

The present invention relates to a paper feeding device that sucks and feeds set paper. The present invention also relates to an image forming apparatus including this paper feeding device.

There is an air-type paper feeding device. Some pneumatic paper feeding devices include a conveyor belt. The conveyor belt sucks the paper. The paper is attracted to the conveyor belt. The conveyor belt is run in this state. As a result, the paper is sent out. An example of a paper feeding device using such suction air is described in Patent Document 1.

Specifically, Patent Document 1 describes an endless conveyor belt that has a plurality of suction holes on the entire surface and suctions and conveys the paper sheets, and a belt that is included in the conveyor belt and sucks the paper sheets through the suction holes. an air suction unit that attracts the paper to the conveyor belt; a floating air blower unit that blows floating air to the paper stored in the paper storage unit to make the paper levitate; and a predetermined area within the conveyance surface of the conveyor belt in the paper conveyance direction. a paper trailing edge detection unit that is disposed at a position and detects passage of a trailing edge of the first sheet of paper through a predetermined position; and a control unit that controls a blowing operation of floating air in a floating air blowing unit;
When the first sheet of paper is being conveyed on the conveyor belt, floating air is blown to float the second sheet of paper, and the blowing of floating air is stopped based on the detection result of the paper trailing edge detection section. The paper feed device used is described. This configuration attempts to prevent the occurrence of double feeding in which a second sheet of paper is attracted to the conveyor belt while the first sheet of paper is being conveyed (see claim 1, paragraph [0011], etc. of Patent Document 1).

Japanese Patent Application Publication No. 2015-016954

Double feeding may occur in paper feeding devices. Multi-feeding means that multiple sheets of paper are conveyed in an overlapping manner. Paper jams may occur due to double feeding. Furthermore, the contents of one page may be printed across multiple sheets of paper. Double feeding causes errors.

There are various reasons why double feeding occurs in air-type paper feeding devices. In an air-type paper feeding device, the air volume is determined based on the paper (standard paper) recommended by the manufacturer of the image forming apparatus. On the other hand, there are many types of paper. Depending on the paper, the air volume determined based on standard paper may not be appropriate. In such a case, double feeding occurs. In addition, paper moisture content, surface roughness, age-related changes in the performance of the fan used to manipulate air, and dust clogging in the air blowing area can also be factors in double feeding. There is a problem in that the ease with which double feeding occurs varies depending on the type of paper and the state of the paper feeding device, and it may not be possible to suppress the occurrence of double feeding.

In the technique described in Patent Document 1, when the trailing edge of the first sheet passes a predetermined position, the blowing of floating air is stopped. This attempts to prevent the second sheet of paper from being attracted to the conveyor belt while the first sheet of paper is being conveyed. However, even with the paper feeding device described in Patent Document 1, double feeding may occur depending on the type of paper and the state of the paper feeding device. For example, if the paper is light (thin), the first paper and the second paper may overlap and be attracted to the conveyor belt. Therefore, the technique described in Patent Document 1 cannot solve the above problem.

In view of the above-mentioned problems of the prior art, the present invention adjusts the volume of air for paper feeding so that the problem (double feeding) does not occur, regardless of the type of paper or the age (hours of use) of the paper feeding device. do.

The paper feeding device according to the present invention includes a set plate, a regulating cursor, a paper feeding belt, a suction device, a feeding mechanism, a distance measuring section, and a control section. Paper is set on the setting plate. The regulating cursor regulates the position of the paper set on the setting plate. The paper feeding belt is provided above the setting plate and the set paper. The paper feeding belt is provided with suction holes. The suction device generates floating air by suctioning air from the paper feeding belt. The suction device sucks the set paper using the floating air. The sending mechanism rotates the paper feeding belt and sends out the paper. The distance measuring unit measures the distance between sheets when the suction device is sucking the sheets. Based on the output of the interval measuring section, the control section recognizes the paper interval. Based on the recognized paper spacing, the control unit adjusts the flow rate of the floating air.

According to the present invention, it is possible to prevent problems such as double feeding (paper feeding errors) regardless of the type of paper or the age (hours of use) of the paper feeding device. During suction of paper, the volume of air for paper feeding can be adjusted so that the paper spacing is such that problems are unlikely to occur.

FIG. 1 is a diagram illustrating an example of a printer according to an embodiment. FIG. 3 is a diagram showing an example of a paper feed cassette according to an embodiment. FIG. 3 is a diagram showing an example of a paper feed cassette according to an embodiment. It is a figure showing an example of a suction device and a delivery mechanism concerning an embodiment. FIG. 1 is a diagram illustrating an example of a paper feeding device according to an embodiment. FIG. 3 is a diagram showing an example of measurement by the interval measuring section according to the embodiment. FIG. 3 is a diagram illustrating an example of the flow of air volume control of floating air and separation air in the printer according to the embodiment. It is a figure which shows an example of the space|interval measurement part based on a modification. FIG. 7 is a diagram illustrating an example of a paper feeding device according to a modification. FIG. 7 is a diagram illustrating an example of a paper feeding device according to a modification.

Hereinafter, a paper feeding device according to an embodiment of the present invention will be described using FIGS. 1 to 7. The printer 100 will be described as an example of a paper feeding device. Printer 100 is also an image forming device. Note that the present invention can be applied not only to the printer 100 but also to other paper feeding devices (for example, multifunction peripherals). The configuration, arrangement, and other elements described in the present embodiment below do not limit the scope of the invention and are merely illustrative examples.

(Printer 100)
A printer 100 according to an embodiment will be described using FIG. 1. FIG. 1 is a diagram illustrating an example of a printer 100 according to an embodiment.

As shown in FIG. 1, the printer 100 includes a control section 1, a storage section 2, an operation panel 3, and a printing section 4.

The control unit 1 controls the operation of the printer 100. The control unit 1 controls operations in jobs such as copying and sending. The control section 1 includes a control circuit 10, an image processing circuit 11, and a communication section 12. The control circuit 10 is, for example, a CPU. The control circuit 10 performs processing and calculations regarding jobs.

For example, the image processing circuit 11 is an ASIC. The image processing circuit 11 generates image data based on the print data received by the communication unit 12. The image processing circuit 11 performs image processing on the generated image data and generates output image data. The output image data is used for a print job.

The communication unit 12 includes communication hardware (communication circuit) and software. The communication unit 12 communicates with the computer 200. The computer 200 is, for example, a PC or a server. The communication unit 12 receives print data from the computer 200. The print data includes, for example, data written in a page description language. The control unit 1 (image processing circuit 11) analyzes data written in a page description language to generate image data. Based on the generated image data, the control section 1 causes the printing section 4 to print.

The storage unit 2 includes RAM, ROM, and storage. The storage is, for example, an HDD or an SSD. The control section 1 controls each section based on programs and data stored in the storage section 2 .

The operation panel 3 accepts settings from the user. The operation panel 3 includes a display panel 31, a touch panel 32, and hard keys 33. The control unit 1 causes the display panel 31 to display messages and setting screens. The control unit 1 causes the display panel 31 to display the operation image. The operation images are, for example, buttons, keys, and tabs. Based on the output of the touch panel 32, the control unit 1 recognizes the operated operation image. The hard keys 33 include a start key and a numeric keypad. The touch panel 32 and hard keys 33 accept setting operations (job-related operations) from the user. For example, the operation panel 3 accepts settings related to reading a document. For example, the operation panel 3 accepts settings for the document size to be read. The control unit 1 recognizes the settings based on the output of the operation panel 3.

The printing section 4 includes a paper feeding section 4a (details will be described later), a paper transport section 4b, an image forming section 4c, and a fixing section 4d. During a print job, the control section 1 causes the paper feed section 4a to supply paper. The paper transport section 4b includes a pair of transport rollers and a transport motor for transporting the paper. The transport roller pair transports the paper. The conveyance motor rotates a pair of conveyance rollers. The control unit 1 causes the paper transport unit 4b to transport the paper.

The image forming section 4c includes, for example, a photosensitive drum, a charging device, an exposure device, a developing device, and a transfer roller. Based on the output image data, the control section 1 causes the image forming section 4c to form a toner image. The control section 1 causes the image forming section 4c to transfer the toner image onto the conveyed paper. The fixing unit 4d includes a heater, a fixing rotating body, and a fixing motor. The heater heats the fusing roller. The paper is conveyed while being in contact with the fixing rotating body. This fixes the toner image on the paper. The control section 1 causes the fixing section 4d to fix the transferred toner image onto the paper. The paper transport section 4b discharges the printed paper to the outside of the machine.

(Paper cassette 5)
Next, an example of the paper feed cassette 5 according to the embodiment will be described using FIGS. 2 to 5. 2 and 3 are diagrams showing an example of the paper feed cassette 5 according to the embodiment. FIG. 4 is a diagram showing an example of the suction device 6 and the delivery mechanism 7 according to the embodiment. FIG. 5 is a diagram illustrating an example of a paper feeding device according to the embodiment.

The paper feeding device includes a paper feeding cassette 5. The paper feed cassette 5 can be pulled out from the printer 100. When replenishing paper, the paper feed cassette 5 is pulled out (opened). After feeding the paper, the paper feed cassette 5 is pushed back.

FIG. 2 is a view of the paper feed cassette 5 viewed from above. As shown in FIG. 2, the paper feed cassette 5 includes a set plate 51 and a regulation cursor. The set plate 51 is made of metal, for example. Paper (sheet bundle) is set on the set plate 51. Paper is set in a vertically stacked state. Note that FIG. 2 shows a state in which no paper is set.

The regulation cursor regulates the position of the paper set on the setting plate 51. The paper feed cassette 5 is provided with a trailing edge regulating cursor 52 and a width regulating cursor 53 as regulating cursors. A portion of the set plate 51 that overlaps with the movement range of the rear end regulation cursor 52 and the width regulation cursor 53 is cut out.

The trailing edge regulating cursor 52 regulates the position of the trailing edge of the set paper. The paper trailing edge is the upstream end in the paper transport direction (sub-scanning direction). The trailing edge regulation cursor 52 is slidable in the paper conveyance direction. The user moves the trailing edge regulating cursor 52 until the trailing edge of the set paper comes into contact with the trailing edge regulating cursor 52. The position of the paper is regulated by contacting with the trailing edge regulating cursor 52 . This prevents paper from shifting.

The width regulation cursor 53 regulates the set paper in a direction perpendicular to the paper conveyance direction (main scanning direction). There are two width regulation cursors 53, which form a pair. Each width regulation cursor 53 can slide in a direction perpendicular to the paper conveyance direction. Each width regulation cursor 53 is linked. In the main scanning direction, when one width regulation cursor 53 is moved toward the center of the paper, the other width regulation cursor 53 also moves toward the center. In the main scanning direction, when one width regulation cursor 53 is moved in a direction away from the center of the paper, the other width regulation cursor 53 also moves in a direction away from the center.

The user moves the width regulation cursor 53 until each width regulation cursor 53 contacts the edge of the set paper. By touching each width regulating cursor 53, the position of the paper in the main scanning direction is regulated. Misalignment of paper in the main scanning direction is prevented. The two-dot chain line in FIG. 2 indicates the center line L1. This center line L1 indicates the center of the conveyance path and the paper in the main scanning direction. Due to the regulation of each width regulation cursor 53, the center of the paper in the main scanning direction matches the center line L1 (center paper passing).

FIG. 3 shows an example of a view of a sheet viewed from the rear end side (upstream side in the sheet conveyance direction) of the sheet. As shown in FIG. 3, a paper feed belt and a spray separation device 8 are provided above the set plate 51 and the uppermost paper among the set (stacked) papers.

Further, the paper feeding cassette 5 (paper feeding device) is provided with an elevating mechanism 54. The elevating mechanism 54 moves the set plate 51 up and down. For example, the elevating mechanism 54 includes a plurality of pulley mechanisms and an elevating motor 55. One pulley mechanism includes a wire 56, a pulley 57, and a winding drum 58. One end of the wire 56 is attached to the end of the set plate 51. The other end of the wire 56 is connected to a winding drum 58. A wire 56 is hung around the pulley 57. The lifting motor 55 rotates the winding drum 58. When raising the set plate 51, the control unit 1 rotates the lifting motor 55 in the direction in which the set plate 51 is raised (in the direction in which the winding drum 58 winds up the wire 56). When lowering the set plate 51, the control unit 1 rotates the lifting motor 55 in the direction in which the set plate 51 is lowered (in the direction to reduce the winding amount of the wire 56).

FIG. 3 shows an example in which two pulley mechanisms are provided. However, there may be more than two pulley mechanisms. For example, pulley mechanisms may be provided at the four corners of the set plate 51. Alternatively, a mechanism for raising and lowering the set plate 51 may be provided using another method without using a pulley.

When printing from the paper feeding device, the control unit 1 maintains the position of the uppermost sheet of the paper stack at a specified position (at a specified height). The position where the vertical distance between the sheet feeding belt 70 and the topmost sheet corresponds to a predetermined sheet feeding interval is defined as the specified position of the topmost sheet. The paper feeding time interval has a length within the range of several mm to several cm (for example, 1 cm).

A paper position sensor 59 is provided within the paper feed cassette 5 . The paper position sensor 59 is a sensor for detecting that the topmost paper is at a specified position. For example, a reflective or transmissive optical sensor can be used as the paper position sensor 59. When the uppermost sheet reaches the specified position due to the raising of the set plate 51, the output level of the sheet position sensor 59 changes. Further, when the position (height) of the uppermost sheet becomes lower than the specified position, the output level of the sheet position sensor 59 changes. The output of the paper position sensor 59 is input to the control section 1.

When raising the set plate 51, the control unit 1 monitors the output level of the paper position sensor 59. When it is recognized that the uppermost sheet has reached the specified position based on the change in the output level of the sheet position sensor 59, the control section 1 stops the raising of the set plate 51. Based on the change in the output level of the paper position sensor 59, during a print job (during continuous paper feeding), when it is recognized that the position of the uppermost paper has become lower than the specified position, the control unit 1 activates the lift motor 55. Rotate. The control unit 1 rotates the lift motor 55 until it is recognized that the uppermost sheet has reached the specified position. The control unit 1 maintains the vertical position (height) of the top sheet at a specified position.

Next, the suction device 6 and the delivery mechanism 7 will be explained using FIGS. 3 to 5. As shown in FIG. 3, the suction device 6 and the delivery mechanism 7 are provided above the set plate 51, the set stack of sheets, the width regulation cursor 53, and the trailing edge regulation cursor 52.

The feeding mechanism 7 includes a paper feeding belt 70, a driving roller 72, a driven roller 73, and a belt motor 74. A plurality of suction holes 71 are provided in the paper feeding belt 70. FIG. 3 shows an example in which the suction hole 71 is circular. The suction hole 71 passes through the paper feeding belt 70. As shown in FIG. 4, the paper feeding belt 70 is endless. The paper feeding belt 70 is wound around a driving roller 72 and a plurality of driven rollers 73 . Belt motor 74 (see FIG. 5) rotates drive roller 72. By rotating the belt motor 74, the paper feeding belt 70 rotates.

As shown in FIG. 3, the center of the paper feed belt 70 in the main scanning direction (direction perpendicular to the paper conveyance direction) is aligned with the center of the paper regulated by the width regulation cursor 53 in the main scanning direction. A paper feeding belt 70 is installed. The width of the paper feeding belt 70 in the main scanning direction is, for example, the same as the width of the smallest printable paper. Further, the lower surface of the paper feeding belt 70 is horizontal.

The left-right direction in FIG. 4 is the sub-scanning direction (paper conveyance direction). A suction device 6 is provided inside the paper feeding belt 70 that is stretched around. The suction device 6 sucks air from a suction hole 71 on the lower surface of the paper feeding belt 70 . The suction device 6 sucks air below the paper feeding belt 70. That is, the suction holes 71 on the lower surface of the paper feeding belt 70 suck air. The air flow caused by this suction is floating air. The generated floating air lifts the top sheet of the paper stack. The uppermost sheet of paper is attracted (sucked) to the sheet feeding belt 70 by floating air (suction by the suction device 6). Note that the floating air also causes the second sheet from the top (the sheet one sheet below the topmost sheet, the second sheet) to some extent.

The suction device 6 is provided with one or more suction fans 60 . FIG. 4 shows an example in which a plurality of suction fans 60 are provided. The suction fan 60 rotates in a direction to suck air from below the paper feed belt 70. By rotating the suction fan 60, the uppermost paper located below the paper feed belt 70 is also attracted together with the air. The uppermost sheet of paper lifted up by the suction comes into contact with the sheet feeding belt 70.

With the paper being attracted to the paper feeding belt 70, the control unit 1 rotates the belt motor 74. The control unit 1 rotates the paper feeding belt 70 in the direction of feeding the paper in the paper transport direction (paper transport unit 4b). The sent paper enters a pair of transport rollers of the paper transport section 4b. Thereafter, the control unit 1 causes the paper transport unit 4b to transport the paper toward the image forming unit 4c and fixing unit 4d.

Next, an example of the spray separation device 8 will be explained using FIGS. 3 and 5. The spray separation device 8 generates separation air. When feeding paper, the control unit 1 causes the spray separation device 8 to generate separation air. In other words, when the suction device 6 suctions the paper, the control section 1 causes the spray separation device 8 to generate separation air. Separation air is air that is blown against the sides of the set paper. The spray separation device 8 sprays separation air onto edges of the paper that are parallel to the paper conveyance direction (sub-scanning direction).

Separation air has the function of creating a gap between sheets of paper. The separation air is air for eliminating contact between the paper that sticks to the paper feed belt 70 (top paper) and the second paper from the top (second paper). In other words, separation air flows into the gap between the top sheet and the second sheet. The separation air can reduce friction between the top sheet and the second sheet. It is possible to reduce the occurrence of continuous conveyance of multiple sheets of paper (multiple conveyance). The separation air can also prevent multiple sheets of paper from being attracted to the paper feeding belt 70. Separation air also has the function of loosening the adhesion of each sheet.

The spray separation device 8 includes a separation fan 80 and a spray duct 81 . The separation fan 80 generates separation air. The control unit 1 rotates the separation fan 80 so that air is blown out from the blowing duct 81. The blowing duct 81 blows out separation air. The blowing duct 81 blows separation air onto the side surfaces (edges parallel to the sub-scanning direction) of the paper. The blowing duct 81 blows air toward the paper at a specified height, for example.

Note that the width position of the paper in the main scanning direction (direction perpendicular to the paper transport direction) changes depending on the paper size. Therefore, the position of the spray duct 81 can be moved in the main scanning direction. For example, the operation panel 3 accepts settings for the size of the set paper. The paper feed cassette 5 (paper feed device) is provided with a duct moving mechanism 82 that moves the position of the spray duct 81. The control unit 1 causes the duct moving mechanism 82 to move the position of the spray duct 81 according to the set paper size. The control unit 1 automatically adjusts the position of the spray duct 81 according to the set paper size. Note that the duct moving mechanism 82 may be a mechanism that manually moves the position of the spray duct 81.

Further, the paper feeding cassette 5 (paper feeding device) is provided with an interval measuring section 9. The distance measurement unit 9 measures the distance between sheets in the vertical direction (height direction) when the suction device 6 is sucking the sheets. Based on the output of the spacing measurement section 9, the control section 1 recognizes the paper spacing.

(Measurement by interval measuring section 9)
Next, an example of measurement by the interval measuring section 9 according to the embodiment will be described using FIG. 6. FIG. 6 is a diagram showing an example of measurement by the interval measuring section 9 according to the embodiment.

FIG. 6 is a diagram illustrating an example of the state (behavior) of a sheet when the topmost sheet is being sucked toward the sheet feeding belt 70. The paper feed belt 70 attracts the uppermost paper by floating air. Due to the influence of the separation air, a void layer (interval, gap) is created between the top sheet and the second sheet. The interval measurement unit 9 is a sensor for measuring the interval in the height direction (vertical direction) of the cavity layer.

Note that the width of the paper in the main scanning direction (direction perpendicular to the paper transport direction) may be wider than the width of the paper feeding belt 70 in the main scanning direction. In such a case, the portion away from the paper feeding belt 70 will sag slightly. In other words, the end portion of the paper in the main scanning direction is located lower than the center in the main scanning direction. During suction, the floating paper becomes convex upward. FIG. 6 also shows a state in which the floating paper has an upwardly convex shape.

For example, the interval measuring section 9 includes a photographing section 9a (camera). The photographing section 9a includes a lamp 9b and an image sensor 9c. The image sensor 9c is, for example, an area image sensor (two-dimensional image sensor). The photographing section 9a is provided at the rear end regulation cursor 52. When the suction device 6 is generating floating air and the blowing separation device 8 is generating separation air, the control section 1 causes the interval measuring section 9 (photographing section 9a) to take an image. Specifically, the control unit 1 turns on the lamp 9b. The control unit 1 causes the image sensor 9c to perform reading while the lamp 9b is turned on.

The direction of the photographing range of the photographing unit 9a (camera) is on the upstream side in the paper conveyance direction when viewed from the trailing edge regulation cursor 52. The photographing unit 9a photographs the paper from the rear end side of the paper. The photographing unit 9a is installed such that the photographing range satisfies the following conditions. For example, the first condition is that the lower surface of the paper feeding belt 70 is included in the photographing range. The second condition is that the uppermost sheet and the second sheet are included in the photographing range while the floating air and separation air are being generated. The third condition is that the center of the photographing range in the main scanning direction (direction perpendicular to the paper conveyance direction) coincides with the center of the set bundle of sheets in the main scanning direction. In FIG. 6, an example of the photographing range of the photographing section 9a (interval measuring section 9) is shown by a broken line rectangle.

The interval measurement unit 9 measures the interval between sheets when the suction device 6 is sucking the sheets. The image sensor 9c of the interval measuring section 9 outputs an analog image signal obtained by photographing. The analog image signal is input to the control section 1. Based on the received analog image signal, the control unit 1 (image processing circuit 11) generates photographed image data. The control unit 1 processes the photographed image data and recognizes the vertical distance (sheet spacing) between the top sheet and the second sheet in the height direction (vertical direction). In this way, the control section 1 recognizes the paper spacing based on the output of the spacing measurement section 9.

In the captured image data, the pixel value of the pixel that captured the paper is, for example, a bright color (eg, white). In the photographed image data, the pixel value of the pixel photographing the gap between the sheets is, for example, a dark color (for example, black). For example, the control unit 1 (image processing circuit 11) performs a binarization process on captured image data. Further, the control unit 1 performs edge enhancement processing on the binarized image data. Thereby, the control unit 1 detects a line (curved line or straight line) indicating the trailing edge of the paper.

The control unit 1 (image processing circuit 11) selects the topmost line (line indicating the highest sheet) and the second line from the top (line indicating the second sheet) among the lines indicating the sheets. Recognize. Then, the control unit 1 determines the vertical distance between the line indicating the top sheet and the line indicating the second sheet. For example, the control unit 1 determines the interval between a pixel indicating the top sheet and a pixel indicating the second sheet for each line parallel to the vertical direction. Then, the control unit 1 determines the average value, maximum value, minimum value, or median value of the determined intervals as the paper interval.

In this way, the spacing measuring section 9 measures the gap in the height direction (vertical direction) between the topmost sheet and the second sheet (one sheet below) among the sheets set on the set plate 51 as the sheet spacing. . Based on the output of the interval measuring section 9, the control section 1 recognizes the paper interval between the topmost sheet and the second sheet.

(Air volume adjustment control)
Next, an example of the flow of air volume control of floating air and separation air in the printer 100 according to the embodiment will be described using FIG. 7. FIG. 7 is a diagram illustrating an example of the flow of air volume control of floating air and separation air in the printer 100 according to the embodiment.

The start in FIG. 7 is the time when feeding of the first sheet of the print job is started. First, the control unit 1 generates floating air and separation air (step #1). Specifically, the control unit 1 starts the rotation of the suction fan 60 and the separation fan 80. After the rotation starts, the control unit 1 accelerates the rotational speed of the suction fan 60 and the separation fan 80. Then, the control unit 1 stabilizes the rotational speed of the suction fan 60 (motor of the suction fan 60) at the first stable speed. Further, the control unit 1 stabilizes the rotational speed of the separation fan 80 (the motor of the separation fan 80) at a second stable speed.

The first stable speed may be a fixed value. In this case, when the paper used as a reference (standard paper) is used, the rotational speed of the suction fan 60 (motor of the suction fan 60) at which the paper interval is appropriate can be set as the first stable speed. Further, the first stable speed may be the rotational speed of the suction fan 60 when feeding the last page of the previous print job. In this case, the control unit 1 causes the storage unit 2 to store the rotation speed of the suction fan 60 when feeding the last page of the print job.

Further, the second stable speed may be a fixed value. In this case, when the paper used as a reference (standard paper) is used, the rotational speed of the separation fan 80 (motor of the separation fan 80) at which the paper interval is appropriate can be set as the second stable speed. Further, the second stable speed may be the rotational speed of the separation fan 80 when feeding the last page of the previous print job. In this case, the control unit 1 causes the storage unit 2 to store the rotation speed of the separation fan 80 when feeding the last page of the print job.

In order to stabilize the rotational speed of each fan, the control unit 1 waits for a predetermined first stabilization time (step #2). During this time, the top sheet of paper floats up, and the paper feeding belt 70 sucks the top sheet of paper. The first stabilization time is a waiting time until the air volume of the suction fan 60 and the separation fan 80 becomes stable. The first stabilization time is, for example, about 10 seconds.

Next, the control section 1 operates the interval measuring section 9 (step #3). Then, based on the output of the interval measuring unit 9, the control unit 1 recognizes the paper interval (step #4). Specifically, the control unit 1 recognizes the vertical distance between the topmost sheet (the sheet in contact with the sheet feeding belt 70) and the second sheet (the sheet one sheet below the topmost sheet).

Next, the control unit 1 checks whether the recognized paper interval is within the allowable range B1 (step #5). When the paper interval is greater than or equal to the minimum value and less than or equal to the maximum value of the allowable range B1, the control unit 1 determines that it is within the allowable range B1. Here, the allowable range B1 is determined in advance. The minimum value and maximum value of the allowable range B1 are determined in advance. For example, an appropriate range of paper spacing that does not cause double feeding or non-feeding of sheets is determined through experiments. In other words, a paper interval that is unlikely to cause trouble is determined in advance. The storage unit 2 stores a predetermined tolerance range B1 in a non-volatile manner (see FIG. 1).

Note that the operation panel 3 may accept the setting of the tolerance range B1. In this case, the user or the person in charge of maintenance can determine the allowable range B1. The control unit 1 causes the storage unit 2 to store the allowable range B1 set on the operation panel 3. The control unit 1 uses the tolerance range B1 stored in the storage unit 2 to confirm.

When the recognized paper interval is outside the allowable range B1 (No in step #5), the control unit 1 checks whether the recognized paper interval is less than the minimum value of the allowable range B1 (step #6). If the recognized paper interval is less than the minimum value of the allowable range B1, it can be said that the paper interval is too narrow. The second paper can be considered to be floating too much. It is thought that the reason for too much floating is that the amount of floating air is too large. There is also a possibility that strong separation air is blowing the second paper upward.

On the other hand, if the recognized paper interval exceeds the maximum value of the allowable range B1, it can be said that the paper interval is too wide. The distance between the top paper and the second paper is too wide. There is a high possibility that paper will not be fed when feeding the next paper. The reason for insufficient floating of the second paper is considered to be that the flow rate of the floating air is weak. It is also possible that the separation air is weak.

Therefore, when the recognized paper interval is less than the minimum value of the allowable range B1 (Yes in step #6), the control unit 1 causes the suction device 6 to reduce the flow rate of the floating air (step #7). Specifically, the control unit 1 lowers the rotation speed of the suction fan 60 (motor of the suction fan 60) of the suction device 6. The control unit 1 may increase the amount of decrease in the rotational speed of the suction fan 60 as the paper interval becomes narrower. Note that even when the recognized paper interval is less than the minimum value of the allowable range B1, the control unit 1 may not change (maintain or reduce) the flow rate of the floating air.

Furthermore, the control unit 1 causes the blowing separation device 8 to reduce the amount of separation air (step #8). Specifically, the control unit 1 lowers the rotation speed of the separation fan 80 (the motor of the separation fan 80) of the suction device 6. The control unit 1 may increase the amount of decrease in the rotational speed of the separation fan 80 as the paper interval becomes narrower. Note that even when the recognized paper interval is less than the minimum value of the allowable range B1, the control unit 1 may not change (maintain, do not reduce) the air volume of the separation fan 80. Further, the control unit 1 may reduce only one of the floating air and the separation air.

On the other hand, when the recognized paper interval exceeds the maximum value of the allowable range B1 (No in step #6), the control unit 1 causes the suction device 6 to increase the flow rate of the floating air (step #9). Specifically, the control unit 1 increases the rotational speed of the suction fan 60 (motor of the suction fan 60) of the suction device 6. The control unit 1 may increase the amount of increase in the rotational speed of the suction fan 60 as the paper interval becomes wider. Note that even if the recognized paper interval exceeds the maximum value of the allowable range B1, the control unit 1 may not change (maintain or increase) the flow rate of the floating air.

Further, the control unit 1 causes the blowing separation device 8 to reduce the amount of separation air (step #10). Specifically, the control unit 1 increases the rotational speed of the separation fan 80 (motor of the separation fan 80) of the suction device 6. The control unit 1 may increase the amount of increase in the rotational speed of the separation fan 80 as the paper interval becomes wider. Note that even when the recognized paper interval is less than the minimum value of the allowable range B1, the control unit 1 may not change (maintain or increase) the air volume of the separation fan 80. Further, the control unit 1 may increase only one of the floating air and the separation air.

After adjusting the air volume of the floating air and separation air, the control unit 1 waits for a predetermined second stabilization time (step #11). The control unit 1 stabilizes the adjusted (changed) air volume. The second stabilization time is a waiting time until the air volume of the suction fan 60 and the separation fan 80 becomes stable. The second stabilization time is shorter than the first stabilization time. This is because the suction fan 60 and the separation fan 80 are already rotating, and the time it takes for the air volume to stabilize is shorter than when they start rotating. For example, the second stabilization time is about 1 to several seconds. Then, the control unit 1 executes step #4 (returns to step #4).

When the recognized paper interval is within the allowable range B1 (Yes in step #5), the control unit 1 maintains the air volume of the floating air and separation air (step #12). Specifically, the control unit 1 maintains the rotational speeds of the suction fan 60 (the motor of the suction fan 60) and the separation fan 80 (the motor of the separation fan 80). Then, the control unit 1 starts sending out (feeding) the sucked paper (step #13). Specifically, the control unit 1 rotates the belt motor 74. As a result, the paper attracted to the paper feeding belt 70 is sent out toward the paper transport section 4b and the image forming section 4c.

Eventually, the control unit 1 stops feeding (feeding) the sucked paper (step #14). Specifically, the control unit 1 stops the rotation of the belt motor 74. For example, a sensor for detecting the arrival of the leading edge of the paper is provided near the most upstream pair of transport rollers of the paper transport section 4b. This sensor detects the arrival of the paper, and the control unit 1 rotates the belt motor 74 until the most upstream pair of transport rollers takes over the paper transport.

Then, the control unit 1 checks whether the feeding of the last sheet (page) of the print job is completed (step #15). If there are still sheets to be fed (No in step #15), the control unit 1 executes step #4 (returns to step #4). On the other hand, when the feeding of the last sheet is completed (Yes in step #15), the control section 1 stops the flotation air and separation air (step #16). Specifically, the control unit 1 stops the suction fan 60 and the separation fan 80. Then, the control unit 1 ends the processing of this flowchart (END).

In this way, the paper feeding device according to the embodiment includes the set plate 51, the regulation cursor, the paper feeding belt 70, the suction device 6, the feeding mechanism 7, the interval measuring section 9, and the control section 1. Paper is set on the set plate 51. The regulation cursor regulates the position of the paper set on the setting plate 51. The paper feeding belt 70 is provided above the set plate 51 and the set paper. A suction hole 71 is provided in the paper feeding belt 70 . The suction device 6 sucks air from the paper feeding belt 70 to generate floating air. The suction device 6 sucks the set paper using floating air. The sending mechanism 7 sends out the paper by rotating the paper feeding belt 70. The interval measurement unit 9 measures the interval between sheets when the suction device 6 is sucking the sheets. Based on the output of the spacing measurement section 9, the control section 1 recognizes the paper spacing. Based on the recognized paper spacing, the control unit 1 adjusts the amount of floating air.

It is possible to measure the distance between the paper sucked by the paper feeding belt 70 and other papers (paper spacing). It is possible to check whether the sheets are close enough to cause double feeding (the interval between sheets is too narrow). In other words, it is possible to check whether the floating air is too strong. You can also check if the paper is far enough apart to cause paper failure. In other words, it is also possible to check whether the floating air is too weak. Based on the recognized paper spacing, it can be confirmed whether the spacing between the paper sucked by the paper feeding belt 70 and other paper is appropriate. As a result of the confirmation, the amount of floating air can be adjusted so that paper spacing is such that double feeding is unlikely to occur.

When the recognized paper interval is greater than or equal to the minimum value of a predetermined allowable range B1 and less than the maximum value of the allowable range B1, the control unit 1 causes the suction device 6 to maintain the flow rate of the floating air. When the recognized paper interval is less than the minimum value of the allowable range B1, the control unit 1 causes the suction device 6 to reduce the flow rate of the floating air. When the recognized paper interval exceeds the maximum value of the allowable range B1, the control unit 1 causes the suction device 6 to increase the flow rate of the floating air. If the vertical distance between the sheets being sucked is too narrow or wide, the volume of floating air can be adjusted so that the distance is appropriate. In other words, it is possible to adjust the floating air so that it is neither too strong nor too weak. The floating air can be set to an appropriate strength (air volume) to prevent double feeding or non-feeding of sheets.

The paper feeding device includes a blowing separation device 8 that generates separation air and sprays the separation air onto the sides of the set paper. When the suction device 6 sucks the paper, the control section 1 causes the blowing separation device 8 to generate separation air. Based on the recognized paper spacing, the control unit 1 adjusts the amount of separation air. It is possible to check whether the interval between the paper sucked by the paper feeding belt 70 and other papers (paper interval) is appropriate. In other words, it is also possible to check whether the separation air is too strong or not, and whether the separation air is too weak. The volume of separation air can be adjusted to avoid double feeding.

When the recognized paper interval is greater than or equal to the minimum value of the predetermined tolerance range B1 and less than the maximum value of the tolerance range B1, the control unit 1 causes the blowing separation device 8 to maintain the air volume of the separation air. When the recognized paper interval is less than the minimum value of the allowable range B1, the control unit 1 causes the blowing separation device 8 to reduce the air volume of separation air. When the recognized paper interval exceeds the maximum value of the allowable range B1, the control unit 1 causes the blowing separation device 8 to increase the amount of separation air. If the distance between the sheets being sucked in the vertical direction is too narrow or too wide, the volume of separation air can be adjusted so that the distance between the sheets is appropriate. In other words, it is possible to adjust the separation air so that it is neither too strong nor too weak. The separation air can be set to an appropriate strength (air volume) to prevent double feeding or non-feeding of sheets.

Based on the output from the interval measuring section 9, the control section 1 recognizes the vertical gap between the topmost sheet of the set sheets and the second sheet, which is the second sheet from the top, as the sheet interval. It can be confirmed whether the distance between the paper that is sucked until it touches the paper feeding belt 70 and the paper directly below it is appropriate. Whether or not a paper feeding error such as double feeding occurs can be determined based on the interval between the topmost sheet and the sheet one sheet below the topmost sheet (second sheet).

The paper feeding device includes a trailing edge regulating cursor 52 as a regulating cursor that regulates the trailing edge of the set paper. The trailing edge of the paper is the upstream end in the paper transport direction. The distance measuring section 9 is a photographing section 9a that is provided on the trailing edge regulation cursor 52 and includes an image sensor 9c. It is possible to photograph the state during suction. It is possible to measure the interval between sheets when viewed from the trailing edge regulation cursor 52 in the leading direction of the sheets (from the upstream side to the downstream side in the sheet conveyance direction). It is possible to determine whether or not the confirmation of the paper being sucked is appropriate.

(Modified example)
Next, a paper feeding device according to a modified example will be explained using FIGS. 8 to 10. FIG. 8 is a diagram showing an example of the interval measuring section 9 according to a modification. 9 and 10 are diagrams showing an example of a paper feeding device according to a modified example.

In the above description of the embodiment, an example was described in which the camera (photographing section 9a) was used as the distance measuring section 9. In a modified example, an ultrasonic sensor 90 is used as the distance measuring section 9 instead of a camera. In other words, the interval measuring section 9 is an ultrasonic sensor 90. The difference is that the control unit 1 recognizes the paper interval based on the output of the ultrasonic sensor 90.

As shown in FIG. 8, the ultrasonic sensor 90 includes a transmitter 91 and a receiver 92. Both the transmitter 91 and the receiver 92 include piezoelectric elements. The transmitter 91 transmits ultrasonic waves. The control unit 1 inputs a predetermined number of pulse signals to the piezoelectric element. The receiving section 92 receives the ultrasonic waves transmitted from the transmitting section 91. The piezoelectric element of the receiving section 92 outputs a voltage according to the intensity (level) of the received ultrasonic wave.

Further, the ultrasonic sensor 90 includes an integrating circuit 93. The integrating circuit 93 charges (integrates) the electric charge output from the piezoelectric element of the receiving section 92 . While receiving a predetermined number of pulses of ultrasound, the control unit 1 charges the integrating circuit 93 with the electric charge output by the piezoelectric element of the receiving unit 92. The output of the integrating circuit 93 increases as the received ultrasonic wave becomes stronger. The control unit 1 recognizes the magnitude of the voltage output by the receiving unit 92. Note that the control unit 1 causes the integrating circuit 93 to discharge the charge before transmitting a predetermined number of ultrasonic waves. The control unit 1 sets the output value of the integrating circuit 93 to zero at the time of receiving the first ultrasonic pulse.

The transmitter 91 and the receiver 92 transmit and receive ultrasonic waves. The transmitting unit 91 and the receiving unit 92 transmit ultrasonic waves to the paper sucked by the paper feeding belt 70 (the topmost paper) and the second paper. FIG. 9 shows an example of installation of the transmitting section 91 and the receiving section 92. In order to position the transmitting section 91 or the receiving section 92 above the uppermost sheet, either the transmitting section 91 or the receiving section 92 is provided above the lower surface of the sheet feeding belt 70. For example, either the transmitting section 91 or the receiving section 92 can be provided outside the paper feeding belt 70 in the main scanning direction (direction perpendicular to the paper conveyance direction). Further, the other of the transmitting section 91 and the receiving section 92 can be provided at the rear end regulating cursor 52. Hereinafter, the transmitting section 91 or the receiving section 92 provided on the trailing edge regulating cursor 52 will be referred to as a cursor sensor 93.

FIG. 9 is a view of the paper set in the suction device 6 as viewed from the main scanning direction (direction perpendicular to the paper conveyance direction). As shown in FIG. 9, a transmitter 91 and a receiver 92 transmit ultrasonic waves obliquely to the plane of the paper. The intensity of the ultrasonic waves received by the receiving section 92 changes depending on the length of the interval between the topmost sheet and the second sheet (sheet interval). For example, the wider the paper interval, the lower the intensity of the ultrasonic waves received by the receiving section 92 may be. The wider the paper interval, the smaller the output voltage of the integrating circuit 93 may become. The narrower the interval between the top sheet and the second sheet, the larger the output voltage of the integrating circuit 93 may become.

When the ultrasonic sensor 90 is used in the interval measuring section 9, the storage section 2 stores the reception output corresponding data D1 in a non-volatile manner (see FIG. 8). The received output correspondence data D1 is data (table) that defines the paper interval corresponding to the output voltage of the receiving section 92. The control unit 1 recognizes the magnitude of the output voltage of the receiving unit 92. The control unit 1 refers to the reception output correspondence data D1 and reads out the paper interval corresponding to the recognized magnitude of the output voltage of the reception unit 92. The control unit 1 compares the read sheet spacing with the allowable range B1.

Here, the trailing edge regulation cursor 52 can slide in parallel to the paper conveyance direction. Depending on the position of the trailing edge regulating cursor 52, the position of the cursor sensor 93 changes in the sub-scanning direction (paper conveyance direction). In order to accurately measure the paper interval between the topmost sheet and the second sheet, it is preferable that the receiving section 92 receives the ultrasonic waves after passing through the topmost sheet and the second sheet. Therefore, a moving mechanism 94 is provided for the rear end regulating cursor 52. The moving mechanism 94 moves the cursor sensor 93 up and down in accordance with the position of the rear end regulating cursor 52. After transmitting the ultrasonic wave, the moving mechanism 94 adjusts the position of the cursor sensor 93 so that it can receive the ultrasonic wave that has passed through the top sheet of paper and further passed through the second sheet of paper.

As shown in FIG. 10, the moving mechanism 94 moves the cursor sensor 93 provided on the trailing edge regulating cursor 52 upward as it moves upstream in the paper conveyance direction. Further, the moving mechanism 94 moves the cursor sensor 93 downward as the trailing edge regulating cursor 52 moves downstream in the paper conveyance direction. Regardless of the position of the trailing edge regulating cursor 52, the receiving unit 92 can receive the ultrasonic waves that have passed only through the topmost sheet and the second sheet.

FIG. 10 shows an example of the moving mechanism 94. For example, the movement mechanism 94 is an orthogonal slide mechanism. A part or all of the moving mechanism 94 is included in the rear end regulating cursor 52. The orthogonal slide mechanism includes a driven link 95, a slide joint 96, and a rotating shaft 97. The rear end regulation cursor 52 is L-shaped. The position of the rotating shaft 97 in the sub-scanning direction is fixed. A cursor sensor 93 is attached to the slide joint 96. When the rear end regulation cursor 52 is slid, the driven link 95 rotates (swings). The rotation of the driven link 95 causes the slide joint 96 to move in the vertical direction.

The sheet feeding device according to the modified example includes a trailing edge regulating cursor 52 that regulates the trailing edge of the set paper as a regulating cursor. The trailing edge of the paper is the upstream end in the paper transport direction. The distance measuring section 9 is an ultrasonic sensor 90. Ultrasonic sensor 90 includes a transmitting section 91 and a receiving section 92. The transmitter 91 transmits ultrasonic waves. The receiving unit 92 outputs a voltage according to the level of the received ultrasound. Either the transmitting section 91 or the receiving section 92 is provided above the lower surface of the paper feeding belt 70. The other of the transmitting section 91 and the receiving section 92 is provided at the trailing end regulation cursor 52. Using the ultrasonic sensor 90, it is possible to check whether the spacing between the sheets being sucked is appropriate.

The trailing edge regulation cursor 52 can slide in parallel to the paper conveyance direction. The paper feeding device includes a moving mechanism 94. The moving mechanism 94 moves a cursor sensor 93, which is a transmitting section 91 or a receiving section 92 provided on the rear end regulating cursor 52, in the vertical direction. The moving mechanism 94 moves the cursor sensor 93 upward as the trailing edge regulation cursor 52 moves upstream in the paper conveyance direction. The moving mechanism 94 moves the cursor sensor 93 downward as the trailing edge regulation cursor 52 moves downstream in the paper conveyance direction.

Although the embodiments of the present invention have been described, the scope of the present invention is not limited thereto, and can be implemented with various updates without departing from the spirit of the invention.

INDUSTRIAL APPLICATION This invention can be used for a paper feeding device.

100 Printer (paper feeding device, image forming device)
1 Control section 51 Set plate 52 Trailing edge regulation cursor 6 Suction device 7 Sending mechanism 70 Paper feeding belt 71 Suction hole 8 Spray separation device 9 Interval measuring section 9a Photographing section 9c Image sensor 90 Ultrasonic sensor 91 Transmitting section 92 Receiving section 93 Cursor sensor 94 Movement mechanism B1 Tolerance range

Claims (6)

A setting board on which paper is set,
a regulating cursor regulating the position of the paper set on the setting plate;
a paper feeding belt provided above the set plate and the set paper, and provided with a suction hole;
a suction device that suctions air from the paper feeding belt to generate floating air, and sucks the set paper by the floating air;
a sending mechanism that sends out paper by rotating the paper feeding belt;
an ultrasonic sensor that is a distance measuring unit that measures the distance between sheets in the vertical direction when the suction device is sucking the sheets;
recognizing the paper spacing based on the output of the ultrasonic sensor;
a control unit that adjusts the air volume of the floating air based on the recognized paper interval;
including;
The regulation cursor includes a trailing edge regulation cursor that regulates the trailing edge of the set paper;
The trailing edge of the paper is an upstream end in the paper conveyance direction,
The ultrasonic sensor includes a transmitter and a receiver,
The transmitter transmits ultrasonic waves,
The receiving unit outputs a voltage according to the level of the received ultrasonic wave,
Either one of the transmitting section and the receiving section is provided above the lower surface of the paper feeding belt,
The other of the transmitting section and the receiving section is provided at the rear end regulating cursor,
The trailing edge regulation cursor is slidable in parallel to the paper conveyance direction,
including a moving mechanism that moves the cursor sensor, which is the transmitting unit or the receiving unit provided on the rear end regulating cursor, in the vertical direction;
The moving mechanism moves the cursor sensor upward as the trailing edge regulation cursor moves upstream in the paper transport direction, and moves the cursor sensor downward as the trailing edge regulation cursor moves downstream in the paper transport direction. A paper feeding device characterized by including a moving mechanism for moving the paper. A setting board on which paper is set,
a regulating cursor regulating the position of the paper set on the setting plate;
a paper feeding belt provided above the set plate and the set paper, and provided with a suction hole;
a suction device that suctions air from the paper feeding belt to generate floating air, and sucks the set paper by the floating air;
a sending mechanism that sends out paper by rotating the paper feeding belt;
a distance measuring unit that measures the distance between sheets in the vertical direction when the suction device is sucking the sheets;
recognizing the paper spacing based on the output of the spacing measuring section;
a control unit that adjusts the air volume of the floating air based on the recognized paper interval;
including;
The regulation cursor includes a trailing edge regulation cursor that regulates the trailing edge of the set paper;
The trailing edge of the paper is an upstream end in the paper conveyance direction,
The paper feeding device is characterized in that the distance measuring section is a photographing section provided at the trailing edge regulating cursor and including an image sensor. The control unit includes:
When the recognized paper interval is greater than or equal to a minimum value of a predetermined tolerance range and less than a maximum value of the tolerance range, causing the suction device to maintain the air volume of the floating air;
when the recognized paper spacing is less than the minimum value of the allowable range, causing the suction device to reduce the flow rate of the floating air;
The paper feeding device according to claim 1 or 2, wherein when the recognized paper interval exceeds the maximum value of the allowable range, the suction device causes the suction device to increase the air volume of the floating air. a blowing separation device that generates separation air and blows the separation air onto the side surface of the set paper;
The control unit includes:
When the suction device sucks the paper, the separation air is generated in the blow separation device,
The paper feeding device according to any one of claims 1 to 3, wherein the amount of separation air is adjusted based on the recognized paper interval. The control unit includes:
When the recognized paper interval is greater than or equal to the minimum value of a predetermined tolerance range and less than or equal to the maximum value of the tolerance range, causing the blowing separation device to maintain the air volume of the separation air;
when the recognized paper spacing is less than the minimum value of the allowable range, reducing the flow rate of the separation air to the blowing separation device;
5. The paper feeding device according to claim 4, wherein when the recognized paper interval exceeds the maximum value of the permissible range, the air volume of the separating air is increased by the blowing separation device. Based on the output of the interval measuring unit, the control unit recognizes a vertical gap between the topmost sheet of the set sheets and a second sheet that is the second sheet from the top as the sheet interval. The paper feeding device according to any one of claims 1 to 5, characterized in that:

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